Field of the Invention
The present disclosure relates to a display device, and more particularly, to a touch sensor integrated type display device capable of recognizing a user's touch operation.
Discussion of the Related Art
In recent years, various input devices, such as a keyboard, a mouse, a joystick, and a digitizer, have been used to allow users to interface with home appliances or information telecommunication devices. However, when the user makes use of these input devices, user's dissatisfaction increases because the user is required to learn how to use the input devices and the input devices occupy space. Therefore, a convenient and simple input device capable of reducing erroneous operations is required. In response to this demand, a touch sensor for enabling the user to input information by directly touching the screen with his or her hand or a pen was suggested.
The touch sensor has a simple configuration capable of reducing the erroneous operations. The user can also perform an input action without using a separate input device and can quickly and easily manipulate a display device through the contents displayed on the screen. Accordingly, the touch sensor has been applied to various display devices.
The touch sensor used in the display devices may be classified into an add-on type touch sensor and an on-cell type touch sensor. The add-on type touch sensor is configured such that a display device and a touch sensor are individually manufactured and then the touch sensor is attached to an upper substrate of the display device. The on-cell type touch sensor is configured such that components constituting a touch sensor are directly formed on the surface of an upper glass substrate of the display device.
There is a problem of an increase in a thickness of the display device because the add-on type touch sensor has a structure in which the touch sensor is mounted on the display device. Further, the visibility of the display device is reduced by a reduction in brightness of the display device resulting from the increase in the thickness of the display device.
On the other hand, the on-cell type touch sensor shares a glass substrate with the display device because the touch sensor has the structure in which the touch sensor is formed on the surface of the glass substrate of the display device. Therefore, a thickness of the display device using the on-cell type touch sensor is less than a thickness of the display device using the add-on type touch sensor. However, the entire thickness of the display device using the on-cell type touch sensor increases because of a touch driving electrode layer, a touch sensing electrode layer, and an insulating layer for insulating the touch driving electrode layer and the touch sensing electrode layer which constitute the on-cell type touch sensor. Further, the number of processes for manufacturing the display device using the on-cell type touch sensor has increased, and thus the manufacturing cost increases.
Accordingly, the need for a touch sensor integrated type display device capable of solving the above-described problems has arisen. An example of the touch sensor integrated type display device includes U.S. Pat. No. 7,859,521.
A touch sensor integrated type display device disclosed in U.S. Pat. No. 7,859,521 divides a common electrode of the display device and allows the common electrodes to serve as touch driving electrodes and touch sensing electrodes. Hence, the touch sensor integrated type display device disclosed in U.S. Pat. No. 7,859,521 measures changes in a mutual capacitance generated in a touch operation and recognizes a touch or non-touch input and a touch position in the touch input.
In the above configuration of the touch sensor integrated type display device, because the touch driving electrodes and the touch sensing electrodes are formed on the same layer, the touch driving electrodes and the touch sensing electrodes are each interconnected by wires according to their functions, so as to avoid contact with different types of electrodes. Namely, the touch driving electrodes are connected to touch driving electrode wires through driving electrode contact holes, and the touch sensing electrodes are connected to touch sensing electrode wires through sensing electrode contact holes. Hence, the touch driving electrodes and the touch sensing electrodes do not electrically contact each other.
However, the touch sensor integrated type display device disclosed in U.S. Pat. No. 7,859,521 has the complex structure, in which both the touch driving electrode and the touch sensing electrode have to be formed on a single common electrode layer, and also separate wires and separate contact holes are required to connect the divided driving electrodes.
As described above, the related art touch sensor integrated type display device had problems of the complex design and a reduction in the display characteristic because of the complex structure, in which various types of display pixels are formed corresponding to a unit touch electrode.